>>108201
Воздух плохо проводит тепло, потому и долго. Если охлаждаться в ледяной воде, можно откиснуть за 15 минут.

https://en.wikipedia.org/wiki/Hypothermia#Water_immersion
>Heat is lost much more quickly in water[35] than in air. Thus, water temperatures that would be quite reasonable as outdoor air temperatures can lead to hypothermia in survivors, although this is not usually the direct clinical cause of death for those who are not rescued. A water temperature of 10 °C (50 °F) can lead to death in as little as one hour, and water temperatures near freezing can cause death in as little as 15 minutes.[37] During the sinking of the Titanic, most people who entered the −2 °C (28 °F) water died in 15–30 minutes.[38]